We have proposed five projects that together address many of the shortcomings in our understanding of how to measure, study and improve efficiency in healthcare. Core B is responsible for data management and analytic support for the data on which the five projects rest. To understand the causes and consequences of differences in the efficiency of healthcare, it is crucial to have: (1) a comprehensive database with sufficient power to characterize detailed patterns of healthcare utilization at the regional, hospital, physician and network levels, (2) a broad array of additional measures drawn from diverse sources that can augment these data, (3) the analytic capacity and oversight to ensure the timely preparation of analytic datasets, and (4) appropriate access to these resources for other investigators. We plan first to maintain a comprehensive and secure database of administrative data including Medicare and Medicaid enrollment files, claims records, and supplementary files. Second, we hope to obtain and manage additional data files required for this P01 and to develop subproject-specific analytic files. We will obtain data from a variety of sources, including the American Board of Internal Medicine, the Minimum Data Set of nursing home care, and Michigan and Texas Blue Cross Blue Shield data. Third, we seek to maintain a computing infrastructure and procedures capable of managing a high volume of patient identifiable, confidential data while ensuring timely and appropriate access to authorized investigators. And finally, we plan to make the research files developed under this P01 available to the research community to the extent permissible under law.